Propeller



ug. 15, 1933. 1. soumis I PROPELLER Filed Feb.' 15, 1929 few, n 8

INVENTOR BY 92m JWM `TTORNEY Patented Aug. 15, 1933 UNITED STATES PATENT ori-TICE Claims.

made to overlap each other on a line drawn` transversely through the blades in which they are positioned. With the above and other objects in view,vmy invention consists in the arrangement, combination and construction of the various parts of my improved device as described in the specification, claimed in my claims and shown in the accompanying drawing, in which: Fig. 1 is a front elevation of a bodying my invention.

Fig. 2 is an elevation of one blade of the propeller shown in Fig. 1, my improved stilfening braces being shown in dotted lines.

Fig. 3 is an enlarged elevation of one end of a propeller blade embodying my invention, certain parts being broken away to show the positioning of the braces therein.

Fig. 4 is a sectional view taken on line 4-44of Fig. 3.

Fig. 5 is a sectional View taken on line 5 5 of Fig. 3.

Fig. 6 is a sectional view similar to that of Fig. 5 with the various component parts in unassembled position.

I have shown a propeller comprising a pair of blades 5 and a hub 6. The blades may be secured in the hub by any well known desired means or the hub may be integrally formed with the blade structures.

The blades are of hollow formation preferably of airfoil shape.` In the particular construction herein shown they comprise top pieces 7, bottom pieces '8 and front pieces 9. The front pieces 9 are welded to their adjacent pieces 7 and 8, as at 10 and 11,V respectiyely, andthe rearward portions of the pieces 7 and 8 are welded together as at 12.

Before the pieces 7 and 8 are welded or otherwise secured together, I provide a series of stiffening stays or braces 13, which are welded along one edge to either the top piece 7 or the bottom piece 8. I have shown them as being welded to the top piece 7, as at 14. These pieces are propeller emdiagonally extended across the propeller blade,-

being preferably positioned adjacent the tip of each blade. As will be seen in Fig. 3, the braces are so extended as to overlap each other on a line drawn transversely of the blade.

After the braces have been secured to one of the inner faces of the blade, such as the inner face of the piece 7, the pieces of the blades are secured together to form the whole. The piece 8 is provided with apertures corresponding to the adjacent edges of the braces 13, such as the apertures l5 shown in Fig. 6, and the stays or braces are -welded through these apertures to the piece 8, as at 16. The edges of the pieces 13 which are to be so welded may be of ridge shape, such as is indicated at 17 in Fig. 6, so as to facilitate the Welding of the same.

I desire it to be understood that various changes may be made in the arrangement, combination and construction of the various parts of my improved device without departing from the Spirit of my invention and it is my intention to cover by my claims such changes as may be reasonably included within the scope thereof. I also desire it to be understood that the word welded is used herein in a generic sense.

What I claim is':

1. -A hollow metal airplane propeller blade depending primarily upon the shell thereof for resisting centrifugal and torsional stresses, the interior of said blade adjacent the tip being provided with braces extending at an angle to both the length and width of said blade, for aiding said blade in resisting tip flutter.

2. In combination with a hollow metal blade for an aircraft propeller depending primarily on its shell for withstanding centrifugal and torsional stresses, a bracing member within said blade adjacent the tip thereof extending angularly with respect to the longitudinal center line of said blade and secured to opposite sides of said shell. A

3. A hollow sheet metal propeller blade having a brace for preventing tip flutter disposed diagonally across the axis thereof adjacent to the tip and being secured to opposite inner sides of the walls of the blade, the brace being connected to the hub solely through the agencyv of the walls of the propeller blade and leaving the major portion of the blade unbraced.

4. A hollow sheet metal propeller blade having a brace secured internally thereof-by a line of welding approximately co-extensive with the length of said brace extending through a slot in one side of the blade adjacent to the brace.

5. A hollow sheet metal propeller blade having a plurality of braces internally thereof, the braces extending diagonally across the axis of the blade and being secured to opposing walls of the blade in order to prevent .tip flutter,` the braces being independent of the propeller hub and being dis- 

